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Switching from triple to double crank - advice needed

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Switching from triple to double crank - advice needed

Old 07-03-18, 02:55 PM
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Fuzzy_Dunlop
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Switching from triple to double crank - advice needed

Iím considering changing the drivetrain on my fast city bike from a triple to a double crank. I rarely ever switch from the largest ring on my crank, never granny gear.

current setup is:
170mm Tiagra 50/39/30 crank
9 speed 11/25 cassette
Deore XT RD
Deore XT FD
Deore LX shifters

Iím interested in upgrading to a standard double or compact crank, probably Ultegra. My interests are weight savings, efficiency, and the respectability of a double crank, lol. I understand I will need to change the cassette and FD. Is there anything else Iím missing?
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Old 07-03-18, 03:44 PM
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csport
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I think there is no need to change the cassette.

If you switch to a "road" FD, you will need a "road" flat bar front shifter.
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Old 07-04-18, 07:27 AM
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andrei_r
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I'm a bit surprised a Deore XT FD can handle a 50T ring. In this case there's no real need in changing the FD nor the front shifter (that is for a compact crank). You'll just want to deactivate the extra click with the limit screws (preferably the lower one, like this the screw is only resisting the spring and you can't accidentally force it). The FD should have enough travel for the narrower Q factor.
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Old 07-04-18, 10:04 AM
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Why not just unbolt the granny gear?
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Old 07-05-18, 11:24 PM
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csport
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Originally Posted by andrei_r View Post
I'm a bit surprised a Deore XT FD can handle a 50T ring. In this case there's no real need in changing the FD nor the front shifter (that is for a compact crank). You'll just want to deactivate the extra click with the limit screws (preferably the lower one, like this the screw is only resisting the spring and you can't accidentally force it). The FD should have enough travel for the narrower Q factor.
I thought about this. Deore FDs are typically optimized for 12t top-middle difference (48-36, 44-32). For a compact (50-34) the difference is 16t. Not sure if this can be worked around.
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Old 07-06-18, 05:32 AM
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Originally Posted by csport View Post
I thought about this. Deore FDs are typically optimized for 12t top-middle difference (48-36, 44-32). For a compact (50-34) the difference is 16t. Not sure if this can be worked around.
True. I've already been through this. Going from triple to double and back to triple. And each time I replaced the FD, probably that was my thinking at the time.

But I think it might be worth a shot to try. While subotimal, it could still be satisfactory. Worst case you'll just cough up the extra dough for the new FD a bit later. It's not like you're losing anything. Maybe just a new inner cable.
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